The purpose of the study is to determine the efficacy and safety of sitaglipin in the treatment of Type 2 diabetes mellitus (T2DM) patients with inadequate glycemic control using metformin and insulin.

DPP-4 inhibitors enhance function of endogenous incretin that helps with glucose homoeostasis. DPP-4 inhibitors have been proved to promote glycemic control without increasing risk of hypoglycemia and weight gain. In addition, they may improve beta-cell function and do not have any known associations with overt cardiovascular or hepatic safety risks.

Addition of sitagliptin to treatment of T2DM patients poorly controlled on insulin +/- metformin has been shown to reduce HbA1c while being generally well-tolerated.

It could be clinically useful to add sitaglipin to treatment regimen of T2DM patients on stable therapy with insulin & metformin. Apart from glycemic reduction, secondary effects like prevention of weight gain, reduction in insulin dose, improved cardiovascular risk profile, etc. may be expected from addition of sitagliptin to treatment.

Inclusion Criteria:

• T2DM patients on metformin and biphasic or basal regimens of insulin
• HbA1c ≥7.3% to ≤8.5%
• Age: 25 to 60 yrs
• Insulin TDD > 10 IU

Exclusion Criteria:

• Use of acarbose, pioglitazone or short-acting insulin analogues at time of run-in phase
• History of type 1 diabetes mellitus
• Creatinine clearance ≤50 mL/min
• Chronic liver & kidney diseases, SGOT/PT≥2.5x upper limit of normal, uncontrolled thyroid disorders , cardiac failure, hemochromatosis, autoimmune disorders, corticosteroid intake.
• BMI >40 kg/m2